1. Field of the Invention
This invention relates to an electronic endoscope for displaying a body-cavity image on a TV monitor, the endoscope having a video-scope having an image sensor and a video-processor. In particular, this invention relates to an adjustment of display-positions of character information including a patient's name, displayed on the monitor with the body-cavity image.
2. Description of the Related Art
In an electronic endoscope, a video-scope includes an optical light guide extended therethrough, which is formed as a bundle of optical fibers. A video-processor includes a light source, such as a halogen lamp. When the video-scope is connected to the video-processor, a proximal end of the optical light guide is optically connected to the light source. Thus, an object to be photographed is illuminated by light radiating from a distal end of the optical light guide, and then an object image is formed on a CCD (Charge-Coupled-Device) provided at the distal end of the video-scope, which is an image sensor. The object image, formed on the CCD, is converted into analog image-pixel signals by photoelectric conversion. The analog image-pixel signals are fed to the video-processor and are suitably processed, so that video signals are generated. The video signals are then output to a TV monitor. Thus, a body-cavity image (for example, an image of a stomach) is displayed on the monitor.
Further, a CRT controller for generating character signals is incorporated in the video-processor. Thus, character information, such as a patient's name and a doctor's name, and a pointer for pointing to a specific portion of the cavity can be also displayed on the monitor with the body-cavity image.
As is well known, the CCD in the video-scope has a smaller size than that of a CCD used in a normal camera. Namely, a number of image pixels, included in one frame, obtained from the video-scope CCD, is less than a number of image pixels, included in one frame, obtained from the normal camera CCD. Therefore, the object image, formed on the CCD in the video-scope, is only displayed on a partial area of the screen of the monitor. Accordingly, in a conventional electronic endoscope, a size of the image-area, within which the object image is displayed, is selectively and optionally changeable when a detailed examination of the diseased portion in the organ is needed. Thus, the object image, displayed on the screen, is enlarged to a predetermined size. Also, a large-sized image-area can be returned to the original-sized image-area.
In accordance with the size-change of the image-area, the character information is also shifted. Namely, a display-position of each item of the character information is changed such that the character information does not overlap the image-area on the screen. A display-position of the pointer is changed only when the pointer is displayed beyond the image-area by the size-change of the image-area.
A control process for changing the displayed-positions of the character information and the pointer is performed under a program in the video-processor. In a source code of the program, which is made by using a programming language, such as the "C" programming language, a description for computing the display-positions corresponding to each item of the character information and the original-sized/the large-sized image-area is needed.
However, the size of the image-area, within which the object image is displayed on the screen, differs from one video-scope to another because of differing characteristics of the CCDs in the video-scopes. Further, a hospital name, a patient's registration number and a patient's sex, and etc., should be also displayed on the screen with the patient's name and age. Therefore, the description for determining the display-positions in the source code increases as the kinds of video-scopes and the amount of character information increases. As a consequence, the structure of the source code becomes complicated, and processing for displaying of the character information cannot be rapidly performed.
Then, as inspection of the source code is difficult, reliability of operation of the electronic endoscope as a whole decreases. Further, the capacity of a memory, in which the program is stored, cannot be reduced.